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Penghui Du, He Zhao, Chenming Liu, Qingguo Huang, Hongbin Cao
The transformation of captopril (CAP), a widely-used thiol drug, was studied with the presence of dissolved model humic constituents (HCs) in a laccase-catalyzed system. Reaction products were analyzed by ultra-performance liquid chromatography coupled to time-of-flight mass spectrometry and condensed fukui function computation. CAP reacted with different model HCs in the enzymatic system for 1 h, ranging from 75% (syringic acid) to 96% (p-coumaric acid). In the absence of HCs, only 15% of CAP was removed through self-coupling...
October 14, 2016: Water Research
David P Hickey
Enzymatic glucose biosensors and biofuel cells make use of the electrochemical transduction between an oxidoreductase enzyme, such as glucose oxidase (GOx), and an electrode to either quantify the amount of glucose in a solution or generate electrical energy. However, many enzymes including GOx are not able to electrochemically interact with an electrode surface directly, but require an external electrochemical relay to shuttle electrons to the electrode. Ferrocene-modified linear poly(ethylenimine) (Fc-LPEI) redox polymers have been designed to simultaneously immobilize glucose oxidase (GOx) at an electrode and mediate electron transfer from their flavin adenine dinucleotide (FAD) active site to the electrode surface...
2017: Methods in Molecular Biology
Sabina Besic, Shelley D Minteer
Although enzymes are highly efficient and selective catalysts, there have been problems incorporating them into fuel cells. Early enzyme-based fuel cells contained enzymes in solution rather than immobilized on the electrode surface. One problem utilizing an enzyme in solution is an issue of transport associated with long diffusion lengths between the site of bioelectrocatalysis and the electrode. This issue drastically decreases the theoretical overall power output due to the poor electron conductivity. On the other hand, enzymes immobilized at the electrode surface have eliminated the issue of poor electron conduction due to close proximity of electron transfer between electrode and the biocatalyst...
2017: Methods in Molecular Biology
Zorica D Knežević-Jugović, Sanja Ž Grbavčić, Jelena R Jovanović, Andrea B Stefanović, Dejan I Bezbradica, Dušan Ž Mijin, Mirjana G Antov
A selection of best combination of adequate immobilization support and efficient immobilization method is still a key requirement for successful application of immobilized enzymes on an industrial level. Eupergit(®) supports exhibit good mechanical and chemical properties and allow establishment of satisfactory hydrodynamic regime in enzyme reactors. This is advantageous for their wide application in enzyme immobilization after finding the most favorable immobilization method. Methods for enzyme immobilization that have been previously reported as efficient considering the obtained activity of immobilized enzyme are presented: direct binding to polymers via their epoxy groups, binding to polymers via a spacer made from ethylene diamine/glutaraldehyde, and coupling the periodate-oxidized sugar moieties of the enzymes to the polymer beads...
2017: Methods in Molecular Biology
Keith J Stine, Kenise Jefferson, Olga V Shulga
Nanoporous gold (NPG) is a material of emerging interest for immobilization of biomolecules, especially enzymes. The material provides a high surface area form of gold that is suitable for physisorption or for covalent modification by self-assembled monolayers. The material can be used as a high surface area electrode and with immobilized enzymes can be used for amperometric detection schemes. NPG can be prepared in a variety of formats from alloys containing between 20 and 50 % atomic composition of gold and less noble element(s) by dealloying procedures...
2017: Methods in Molecular Biology
Joel L Kaar
Widespread interest in the use of room-temperature ionic liquids (RTILs) as solvents in anhydrous biocatalytic reactions has largely been met with underwhelming results. Enzymes are frequently inactivated in RTILs as a result of the influence of solvent on the enzyme's microenvironment, be it through interacting with the enzyme or enzyme-bound water molecules. The purpose of this chapter is to present a rational approach to mediate RTIL-enzyme interactions, which is essential if we are to realize the advantages of RTILs over conventional solvents for biocatalysis in full...
2017: Methods in Molecular Biology
Andriy Bilichak, Igor Kovalchuk
DNA methylation is a reversible covalent chemical modification of DNA intended to regulate chromatin structure and gene expression in a cell- and tissue-specific manner and in response to the environment. Cytosine methylation is predominantly occurring in plants, and cytosine nucleotides in plants can be methylated at symmetrical (CpG and CpHpG) and nonsymmetrical sites. Although there exists a number of various methods for the detection of cytosine methylation, most of them are either laborious or expensive or both...
2017: Methods in Molecular Biology
Carolina Anazco, Alberto J Lopez-Jimenez, Mohamed Rafi, Lorenzo Vega-Montoto, Ming-Zhi Zhang, Billy G Hudson, Roberto M Vanacore
The 7S dodecamer is recognized as an important structural crosslinking domain of collagen IV networks that provide mechanical stability to basement membranes, a specialized form of extracellular matrix essential for the development and maintenance of tissue architecture. Although the 7S dodecamer is stabilized by covalent crosslinking, the molecular mechanism by which such crosslinks are formed has not been revealed. Here we aimed to identify the enzyme(s) that crosslinks the 7S dodecamer and characterize its expression in the kidney glomerulus...
October 21, 2016: Journal of Biological Chemistry
Li-Shun Zhang, Qing-Li Zhao, Xin-Xin Li, Xi-Xi Li, Yan-Ping Huang, Zhao-Sheng Liu
A hybrid monolith incorporated with mesoporous molecular sieve MCM-41 of uniform pore structure and high surface area was prepared with binary green porogens in the first time. With a mixture of room temperature ionic liquids and deep eutectic solvents as porogens, MCM-41 was modified with 3-(trimethoxysilyl) propyl methacrylate (γ-MPS) and the resulting MCM-41-MPS was incorporated into poly (BMA-co-EDMA) monoliths covalently. Because of good dispersibility of MCM-41-MPS in the green solvent-based polymerization system, high permeability and homogeneity for the resultant hybrid monolithic columns was achieved...
December 1, 2016: Talanta
Quan-Xing Mao, Lu Han, Yang Shu, Xu-Wei Chen, Jian-Hua Wang
In the practice of in vivo imaging with carbon nanodots (CNDs) as probe, the volume of CNDs solution introduced into living body should be kept at minimum, and a higher concentration is needed to ensure sufficient quantity of the probe for obtaining bright image. Therefore, the improvement on biocompatibility of the CNDs is among the most important and critical issues. We report herein the improvement on the biocompatibility of CNDs with modification by ionic liquid. Amide group functionalization of carbon nanodots is first conducted through microwave irradiation, followed by coupling the ionic liquid 1-carboxymethyl-3-methyl imidazolium bromide on the surface of the Amide-CNDs via covalent conjunction to produce the modified carbon nanodots (IL-CNDs)...
December 1, 2016: Talanta
Yan Zhang, Jingjing Jiang, Min Li, Pengfei Gao, Ying Zhou, Guomei Zhang, Shaomin Shuang, Chuan Dong
Herein, a novel, high sensitive, and specific colorimetric sensor for cysteine (Cys) based on pectinase protected gold nanoparticles (P@AuNPs) has been demonstrated for the first time. The P@AuNPs were synthesized by "MW-assisted heat method" and were characterized by UV-vis, TEM, FT-IR and zeta potential techniques. Cys could cause the aggregation of P@AuNPs due to formation of the strong covalent Au-S bond and electrostatic binding. As the Cys concentration increased, the color of the solutions gradually changed from wine-red to blue as well as the large absorption band shifted from 523 to 650nm upon P@AuNPs aggregation...
December 1, 2016: Talanta
Anna Alexandrovna Arkhipova, Grigory Il'yich Tsysin, Mikhail Alexandrovich Statkus, Mikhail Alexandrovich Bol'shov, Irina Filippovna Seregina, Yury Alexandrovich Zolotov
A comparison of the efficiency of sorbents obtained by different methods of non-covalent immobilization of β-diketones on some low-polar matrices with respect to extraction of rare earth elements (REEs) was carried out. It was shown that sorbents containing reagent amounts of 1-8mmol/g can be obtained by sorption of reagents on low-polar matrices from aqueous and aqueous-organic solutions, and the value for the maximum capacity of the sorbent correlates with the specific surface of the matrix. Similar sorbents were also prepared by impregnating the matrix with reagent...
December 1, 2016: Talanta
Mingxue Wu, Gang Chen, Jiutong Ma, Ping Liu, Qiong Jia
Covalent organic frameworks (COFs) are an emerging class of porous organic frameworks with diverse promising applications. Herein, we presented the first example of cross-linked hydrazone COFs (cross-linked COFs) coating via thiol-ene click chemistry for solid phase microextraction (SPME). Strong covalent bonds and interlayer of the prepared networks ensured the adsorption capacity and durability of the novel SPME fiber. π-π conjugated structure existed because of abundant phenyl rings and -C=N groups in the cross-lined COFs...
December 1, 2016: Talanta
Wenchang Wang, Juntao Wang, Shuaihua Zhang, Penglei Cui, Chun Wang, Zhi Wang
A novel covalent organic framework, Schiff base network-1 (SNW-1), was synthesized and used as a solid-phase microextraction (SPME) fiber coating material. The SNW-1 coated SPME fiber was fabricated by a covalent chemical cross-linking between the SNW-1 nanocomposite and a silanol-functionalized stainless steel wire substrate. Scanning electron microscopy and nitrogen isothermal adsorption results indicate that the new fiber coating exhibited a porous, homogenous surface with the Brunauer-Emmett-Teller surface of 668m(2)g(-1)...
December 1, 2016: Talanta
Svetlana V Fedorenko, Svetlana L Grechkina, Asiya R Mustafina, Kirill V Kholin, Alexey S Stepanov, Irek R Nizameev, Ildus E Ismaev, Marsil K Kadirov, Rustem R Zairov, Alfia N Fattakhova, Rustem R Amirov, Svetlana E Soloveva
The present work introduces deliberate synthesis of Gd(III)-doped silica nanoparticles with high relaxivity at magnetic field strengths below 1.5T. Modified microemulsion water-in-oil procedure was used in order to achieve superficial localization of Gd(III) complexes within 40-55nm sized silica spheres. The relaxivities of the prepared nanoparticles were measured at 0.47, 1.41 and 1.5T with the use of both NMR analyzer and whole body NMR scanner. Longitudinal relaxivities of the obtained silica nanoparticles reveal significant dependence on the confinement mode, changing from 4...
October 14, 2016: Colloids and Surfaces. B, Biointerfaces
Maria Chatzinikolaidou, Charalampos Pontikoglou, Konstantina Terzaki, Maria Kaliva, Athanasia Kalyva, Eleni Papadaki, Maria Vamvakaki, Maria Farsari
The regeneration of bone via a tissue engineering approach involves components from the macroscopic to the nanoscopic level, including appropriate 3D scaffolds, cells and growth factors. In this study, hexagonal scaffolds of different diagonals were fabricated by Direct Laser Writing using a photopolymerizable hybrid material. The proliferation of bone marrow (BM) mesenchymal stem cells (MSCs) cultured on structures with various diagonals, 50, 100, 150 and 200μm increased significantly after 10days in culture, however without significant differences among them...
October 13, 2016: Colloids and Surfaces. B, Biointerfaces
Satoshi Habuchi, Takuya Yamamoto, Yasuyuki Tezuka
We demonstrate a method for the synthesis of cyclic polymers and a protocol for characterizing their diffusive motion in a melt state at the single molecule level. An electrostatic self-assembly and covalent fixation (ESA-CF) process is used for the synthesis of the cyclic poly(tetrahydrofuran) (poly(THF)). The diffusive motion of individual cyclic polymer chains in a melt state is visualized using single molecule fluorescence imaging by incorporating a fluorophore unit in the cyclic chains. The diffusive motion of the chains is quantitatively characterized by means of a combination of mean-squared displacement (MSD) analysis and a cumulative distribution function (CDF) analysis...
September 26, 2016: Journal of Visualized Experiments: JoVE
Dong-Eog Kim, Jeong-Yeon Kim, Su-Kyoung Lee, Ju Hee Ryu, Ick Chan Kwon, Cheol-Hee Ahn, Kwangmeyung Kim, Dawid Schellingerhout
Direct thrombus imaging visualizes the root cause of thromboembolic infarction. Being able to image thrombus directly allows far better investigation of stroke than relying on indirect measurements, and will be a potent and robust vascular research tool. We use an optical imaging approach that labels thrombi with a molecular imaging thrombus marker - a Cy5.5 near-infrared fluorescent (NIRF) probe that is covalently linked to the fibrin strands of the thrombus by the fibrin-crosslinking enzymatic action of activated coagulation factor XIIIa during the process of clot maturation...
September 25, 2016: Journal of Visualized Experiments: JoVE
Wei Xu, Jianyuan Zhao, Shimin Zhao
The signals of intracellular metabolites are integrated into cellular signaling networks by forming metabolite-derived posttranslational modifications or by non-covalently binding to proteins. These signals serve to coordinate cell metabolism and to regulate various aspects of cell physiology. © 2016 IUBMB Life, 2016.
October 20, 2016: IUBMB Life
Parvin Akbarzadehlaleh, Mona Mirzaei, Mahdiyeh Mashahdi-Keshtiban, Karim Shamsasenjan, Hamidreza Heydari
Human serum albumin (HSA) is a non-glycosylated, negatively charged protein (Mw: about 65-kDa) that has one free cystein residue (Cys 34), and 17 disulfide bridges that these bridges have main role in its stability and longer biological life-time (15 to 19 days). As HSA is a multifunctional protein, it can also bind to other molecules and ions in addition to its role in maintaining colloidal osmotic pressure (COP) in various diseases. In critical illnesses changes in the level of albumin between the intravascular and extravascular compartments and the decrease in its serum concentration need to be compensated using exogenous albumin; but as the size of HSA is an important parameter in retention within the circulation, therefore increasing its molecular size and hydrodynamic radius of HSA by covalent attachment of poly ethylene glycol (PEG), that is known as PEGylation, provides HSA as a superior volume expander that not only can prevent the interstitial edema but also can reduce the infusion frequency...
September 2016: Advanced Pharmaceutical Bulletin
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